Drafting apparatus



fsept. 19, 1944.

A. LANGSNER DRAFTING .APPARATUS Filed Dec. yl5, 1937 2 Sheets-Sheet 1 Spt. 19, 1944.` A. LANGSNER DRAFT ING APPARATUS 1 Filed Deo. 15, 1937 lllIl 2 Sheets-Sheet 2 velements operating on pulleys Patented Sept. 19, 1944 ass-8,521 DRAFTING APPARATUS Adolph Langsner, Chicago, Ill., assigner to Eugene Dietzgen Co., Chicago, Ill., a corporation of Delaware Application December 15, 1937, serial No. 179,832 (el. ca -79) isClaims. My invention relatesin general to parallel motion devices and more especially to drafting equipment embodying parallel motion mechanism,.the invention relatingmore particularly to a device adapted for attachment on a drawinglboard or table in order to support a ruling guide element, such as a straight edge, for free and unrestricted movement within a drafting area on Vthe board or table, while maintaining the ruling element in an adjusted relative angular relation with respect to the board or table throughout. the movement of the guide element within said drafting area. l f' An important object of the invention is to provide parallel motionV apparatus in which the element supported for parallel movement is carried on a jointed arm, including llexible; endless belt means for maintaining the supported device in a desired alignment, regardless ofthe movement of thearm. f

Another important object of the invention is to provide improved parallelmotion apparatus comprisingv a pair Vof arms connected together for relative angular movement and adapted, one for attachment on a Supporting base and the other to carry the device supported for parallel movement, the arms embodying ilexible driving at the opposite ends of the arms in order to'maintain parallel movement of the ruling guide.

Another important object resides in providing Vapparatus of the character mentioned wherein the relatively movable arms are of simplied construction, each comprising tubular connecting means extending between pulley housings and supporting the housings in spaced relationship whereby an inexpensive, lightweight, and adequately rigid arm construction is provided;

, a further object being to utilize the tubular imeans for the purpose of housing and protecting the flexible driving element, while at the same time holding the pulley housings in spaced relationship. f

Another important object resides -in utilizing a flexible driving element on each arm for drivingly connecting thefpulleys at the opposite ends of the arms; a further object `being to provide improved means for connecting the opposite ends of the driving element in a manner permitvting adjustment of the tension thereof when inplace on thepulleys. l

Anotherimportant object resides in providing va novel pulley housing-construction to facilitate the insertion or application of the exible driv, ing element onvthe enclosed: pulleys withthe element extending between said' pulleys through the tubular rods. f I g 'Another important Objectis to provide yielding'means neatly and compaotly arranged to normally urge the ilexible driving elementk in one direction on said pulleys; a further object being to utilize ahelical' spring extending within one of the tubularfspacing and .enclosing members, withthe flexible driving element extending axially throug said helical .,spring, whereby to conserve space andfpermit thespring and drivingelement-to be snugly enclosed while freely operable within the tubularelement. 1

Another important object is to'simplify the operation of assembling parts forming aparallel motion mechanism of thev character mentioned. Among the numerous other objects and advantages of myv present invention is the provision of neat, compact and attractive parallel motion mechanismf wherein the Weight of moving parts isreduced to a minimum, allof the parts being entirely enclosed and housed against'mechanical forces and from deterioration v'through exposure to'fthe atmosphere, the novel` structural features of the apparatus, vin addition, lending themselves-to the provision of Van attractive vstreamlined appearance in ythe'flnished article.

The foregoing and Y advantages and inherent functi'ons'xfl my present invention will become apparent `vas the same is more fully understood fromltliel following description which, taken-in connection with the accompanying drawings- 'disclosesl a vpreferred embodiment ofthe invention. g Referring to the drawings,J j

Figure 1 is a top plan View ofY parallelj motion mechanism embodying rny present invention, parts of the apparatus being4 `broken away. to illustrate the internal construction; 'f

Figures 2 and 3 are sectionalviews taken Vsubstantially along the lines 2 2 and n3 3, rrespectively, in Figure l;

Figure 4 Y-is an enlarged-viewer afporton of the device shownin Figure' 1;'and l f Figures 5, 6 and -7 -are sectional views, 1 respectively, taken substantially along linesSY-5 VDrising meansl forming v Y:and I3 connected together fori relative rotation- .and s6 in Figure 1-anuia1ongf1ine 1511111 Figure 6. f Y

To illustrate my inventiomI have shown lon the drawings parallel motion "mechanism comapairofl arm elements II Labout an faxisl lfadjacent` an end; ofeacharm,

at the opposite 'end- 0f` means I1 being providedthe arm II for anchoring it on a drafting board or table for relative rotation about a stationary axis preferably formed by a stationary pin I9. The end of arm I3, opposite from the pivot I5, car-ries means 2l for supporting an element 23 for parallel movement, said element, in the illustrated embodiment, comprising drafting guide means adapted to be moved throughout a drafting area on the drawing board orta'ble on which the mechanism is or may be attached.

The arms II and I3 are preferably of substantially identical construction/and may comprise each a pair of housing elements 25 and a pair of hollow, tubular spacers 21, the opposite ends of which are secured to theV housing elements 25 to support the same in spaced-apart relationship. The housing elements of the arm I I are individually identified by the numerals I and I2, while the corresponding elements of the arm I3 are identified by the numerals I4 and I6.

The housing elements preferably are ofsubstantially identical construction for convenient and inexpensive fabrication, and they preferably comprise, generally, shallow, cylindrical casings,

each having a cylindrical rim 29 and a closed end Wall 3I, the opposite end wall 3|, concentrically an annular flange 33 preferably formed integral withv the wall 3l. and extending inwardly ofsaid wall in position to form a seat of any suitableror preferred construction, and which, as shown on the drawings, may be a roller or ball bearing. y

The casings l0 and I2, which areat the opposite ends of the arm Il, as wellpas the casing I6, which is at lthe free end of the arm I3, are arranged with their open ends facing downwardly toward the surface on which the device is mounted. The casing is secured to the arm II, is arranged with its open end facingupwardly, oppositethe open end of the, casing I2, so that the casings I2 and I4 cooperate to form a housing. This housing encloses a pulley being open. The end formed by the cooperating casings I2 and. I4. The pulley is mounted on a pin 4I and journalled for rotation in the bearings 35 of the casings I2 and I4, the pin 4I serving to hold the casings together by cooperation with said bearings. It

ing a part ofthe means I1 by which the device is or may be fastened upon the drawing board or table. The housing element I0 is journalled on the pin I9 by means of its bearing 35. The pin I9 also `carries a pulley 43 extending within the housing element I0 and having a 45 extending yadjacent and within the rim 29 of the casing. The pulley 43 has Va hub xed on the pin or shaft I9 so that the pulley is held from rotation with respect to the mounting means I9 andthe table on which the device is or may be attached.

The open end of the housing 25 may be and preferably is enclosed by vsuitable cover means 46 f'supported on the shaft I9-, and while such-cover means may takefany suitable or convenient form i and may be formed on or carried bythe pulley 43if desired, I prefer tomountathe cover. for

for a bearing 35 `'freerotational i'novi/ement.k on the-pin VI9 so that the casing Ill and cover 46 may form a closed casing around the pulley 43.

In the illustrated embodiment the device or element 23 supported for parallel movement comprises a bracket 41 supporting straight edge elements 49 at right-angles, one with respect to the other, although it is, of course, apparent that the invention is not necessarily limited to the specific character of the supported element 23. Means 2I is provided to mount the supported element 23 upon the casing I6 at the free or swingin'g end of the arm I3, the means 2l comprising a pulley 5I carried on a pin 53 and journalled Y for rotation on the housing element I6 by means within the rim 29, carries I4 at the end of the arm I3,.which Y 31 having a rim 39V extending in K the peripheral portions of the compartmentof the bearing 35 in said housing.

It will be noted that the pin 53 is fast with the pulley 5I, the pin having a head extending downwardly of and projecting from the lower, open end of the housing in position to support the bracket 41 which forms a part of the supported element 23. The bracket 41 is carried by the pin 53, and means, including the clamp 55, is provided for adjusting the relative angular relationship of the supported device 23 with respect to the pulley 5I and for locking the parts in a desired adjusted relationship, the angularity of which may be determined on a scale 51 carried by the pulley 5I. At its end opposite the head the pin 53 projects upwardly of the bearing through a central opening formed in the wall 3I of the housing I6, and this end is provided with means for attaching a knob or hand piece 59.to aid in the manipulation of the device. In the illustrated embodiment the hand piece 59 is fastened on the spin 53 against turning movement.

The rim 29 of each of the casings I0, I2, I4 and I6 is or may be formed with a pair of preferably integral projections 6I extending tangentially of the rim 29, said projections on each casing being parallel and spaced apart on opposite sides of the casing. The projections 6I are each formed with a preferably accurately defined seat 63 adapted to snugly receive the end of Vaspacer tube 21. VThe bottom of each seat is connected with the interior of the casing on which'it vis formed, bymeans of an opening 65 so that when the end of a tube 21 is assembled in the seat 63 the interior of the tube is connected with the interior of the casing in tangential alignment with the rim of the pulley therein.

The arms II and I3 are assembled readily by press-fitting the ends oi the Atubular members 21 into the sockets or seats 65, the tubes forming adequately rigid connection between Athe casings and serving to maintain the casings in accurately spaced apart relationship, at the same time providing an extremely lightweight arm strucure.

It will be noted that the casings I-2 and vI4 cooperate to form a' substantially closed housing for the pulley 31; that the housing Ill, in conjunction with the cover means 46, likewise forms asubstantial enclosure for'the pulley 43; and that the pulley l5I- has a .portion carrying an outstanding flange 56 that cooperates with theopen v end of the casing I'VG'to form an enclosure for the tape carryingportions of the pulley 5I.

The rims of the pulleys V43 and 5I are each -formed preferably Vwith a single, peripheral groove, while the pulley 31 at the 'pivotally connected ends :of the arms H and I3 is 'formed Vwith a pair yof' grooves in its The grooves -iifilallof the pulleys 3143-'and 5I,however,are *of like width and depth, `and are adapted to receive exible :driving means SIipreferably comprising an-endless 'belt inl` each .lof l th'efiarms .I I.- and |3; These belts may Vconveniently f'comprisev lengths fof metal tape,"thel oppositevends of Veach-:tape being connected togetherby .fastening .means-'.69

yallowing for -`adjustment so :that the flexible drivingmeans mayk be fdrawn .up .to :a: desired tension on the carrying pulleys!Mv L The tape-like element'sforming: the-exible driving means may :be applied. on1theV pulleysin -eachl arm by; threading, ithei; same .endwise :throughv the openfside of'zthe :housingielement 10,1 in thecase' of arm I:I,.and.through;theuopen Vside of'. the housing element |61,iinfthe caseffof .through the tubes 21 and.: arounclV the'ipulleys .in applying the same. :addition,-openingsx62 may, if desired,4 be formed inxthe top of .the heus; ings for thispurpose. Afterithe exibledriving means have thus beenf as'sembled.-in.-eachotthe -arms I and I 3, the ,abuttingrends of. each may be connected together byfthe'connectors' .6 9'... Then 'the pulleys Nv43 and 5I may .beassembledinplaca =.The ,connectorsfull each comprisefa stem l1.I having a diametral=sloti13 at oneend adapted itoreceive anend.` of vtheexble driving member .threaded end 1,1which Aga,lso isgpro vided witha ldiametral Hslotflil, A onnectorpiece 8| isprovided, for attachment r inL .relatively permanent fashion upon the end of 'the flexible .driving-.clef

ment.` This piece 8| is of plate-like form and is adapted toslidinglygt the Lslot 19. It has a necked portion 83 of width not greater than the diameter of the threaded portion of the pin so that a nut 85 on the threaded portion 11 of the stem may encircle the necked portion 83.

The connecting piece 8| has a head 81 extendingl outwardly of the slot on opposite sides of the stem in position to rest upon one end of the nut 85. Consequently, after the driving bands 61 have been assembled in the arms II and I3, as heretofore described, theabutting ends of the bands may be connected together simply by attaching one of said ends in the slot 13 and attaching the other end on the connector piece 8|. This done, it is merely necessary to thread the nut 85 on the stem 1I and draw the same down until a Adesired tension is obtained in the driving element. The nut sockets therein adapted to receive a tool to facilitate the tighteningV of the nut on the stem, which may be accomplished readily through the openings at the base ofthe projections 6I.

85 may have radial The flexible driving belts kIi1 are tightened sufciently to provide appreciable irictional grip upon the pulleys. Since the.V pulley V43 is held against rotation with respect to the drawing board or table, it will hold the ilexible connector 61 of the arm I I because of the frictional driving Y engagement between said pulley 43 andthe ilexible connector. As the arm I is swung about the the pulley 31. It will be apparent, however, that' .the springs may be' anchored tubes 21 without binding.

pivotipin I9, however, the vdriving' connection betweenf-thezflexible" connector of the arm' I'I `and the .pulleyf31:,willrcause said pulley torotate 4in the..=casing :I2 Vthrough an angular displacement equal-at all times tothe angularmovement of the armfI I- aboutthepivotpin: I9. .In likexfashion,

the iiexible-"connector 61.3of the arm I3, Vthrough its frictional driving .engagement` on the pulley 3:1. and onthe pulley. 5|,insures that theizangular movement "of-the pulley 5I' with respect-to the housirigI'Ii. is at" all .times equal Sto the. angular movement of the housingllwithrespect to the pulleyf: 38, rtherebyf'finsuring that. the. supported element-2231s atyall I.times maintained in an; ad-v 'justed-,fangularrelationship with respect tothe board.i or table. onwhich the device ismounted,

regardlessfof'thelmovement of the armsv II and I-3-The1 desired .angular relationshipgof course, may :be-adjustedby'manipulating the means 2|, including thev clamp55, as is well'understood in parallel motion mechanism. s `=.-:In order-to'ffacilitate.manipulation of the de.- vice, 1I' provide"v means operating: vto normallyA urge .thebands 61 iofthe severalzarms `inopposite di'- rections upon-.the pulley-.31. sothat when the de'- viceis 'in anormal or'neutral position-the resilient urge exerted on -the pulley 31. is lsubstantiallyV -equal and opposite. `AWhen the device isv moved from theneutral positionzin' onef'direction,v the -resilient Itensioning. means.v in one.. arm will :be 'caused to exertazgreater for'ceonthe Vpulley l31',

While thefforce produced byfthe :tensioning means in the "other arm will be reduced..V -The opposite elfect iscreated when thedevice'is Ymoved from the Yneutralfpositionlinhthe other direction'. so

that the yielding .means .at all ztimes=normally urges the mechanismto. return to the'normal or neutral. position, whichgof course, .may be fadj.usted`.tov :any :position within the.fdrafting` areaI merely by slipping the drivingV means onthe pulleysi.- y f f :An important featuref of my '.presentinvention iis fthe arrangement vof the Y.resilient tensioning .means neatlywand `compactly .within-.the :tubular :members ,-21.-. To' this end, the resilient :tension- .1ingqme'ans "mayf comprise helical :springs 9 I tone for each of the arms Il' and I3. This helical spring preferably has an internal diameter appreciably greater than the largest cross-sectional dimension of the flexible driving element V|51 so thatsaid spring may be assembled in position encircling a portion of the driving element, Without, however, binding upon the element or interfering in its operation. The spring 9| also is of a sizeto t freely within one of the spacing One end of the spring is attached to the stem 1I as by means of a hook 93 fastened on said L stem,.preferably byrmeans of one of the'pins 15 by which the end of the flexible driving element is secured to the stem. The other end of the spring has a preferably hooked portion forming an elongated loop and is secured adjustably upon a boss 91 formed `within the marginal ange 29 of one of the housing elements 25, and I prefer to formthe spring anchoring boss 91 in the housing element I4 for the arm I3 and in the housing I2 for the arm Il, so that the anchored ends of the springs of both arms are connected on the elements I2 and I4 housing the arms in which they are assembled.

To secure the springen the anchoring boss,-

at either endof preferahlyat head adapted toy overlie theg looped portion 95- of i the spring; to .holdtha samericlal'nlt-` ingly .upong the i end of the anchoring bloss 91; Thestu'dnv 99 `has a; threaded. 'stem extending throughathe-boss. and having an end: exposedv outwardly of the marginal flange 29i.of. the hous` ing: inlwhich itis mounted. exposed end maybe slotted. as .at I 0 IV or otherwise. formed to receivezaV turning element,;suchf asascrew-driver', to .facilitate the tightening 'oithestud ori loosen-f,

ing. thereofA in anchoring.4 vthe spring,V or. releasing thesame foradjustmenti l The .device oimy presentinvention-has several advantages, v.including simplicity ofi; construction of the arms Il. and |3, .lightness-.in weight; oi moving parts the Vprovisiorr of .-simple, .easilyA ope- `erate'd means for tensioning the; flexible; driving construction and. arrangement of the several; parts:

.without departing fromithe spiritv or. scopeof the invention, or sacrificing any .of-its. attendant ad'.- vantages, the form herein described being apre# ferred .embodiment for. the -purpose of illustrating theinvention;r but'lddnot herein claim the broader aspects of the invention, nor the com bination including, thev adjustable connector- E9, since the same forms the. subjectfmatter of., claims in :my co-pend-ing applicatior'r,V Serial. No.; 212,335, l:filedfMay 8;"19.39.A` The invention is hereby claimed as follows:v

,; 1..y fln'apparatus of. the character descrided;l in-Y cluding aframecarrying, in spacedv relationship thereon, av pair oitransmission members forming supports angularlyfmnvableiwitn respectv tn the frame,r and-.iiexible` driving means comprising an flexible driving: means,xan adjustable member i elongated tension member; Onandextending be: tween said supports and, drivinglyinterconnectingv the same,1saidframeprovidinga tubular duct between said supports;v4 for housing portions of said; tension member; between said supporta the combination, withv said ltension-'member and said trame,Y of.a=.,.helicalspring encircling a portion of said tension member withinsaid duct and inter.- connected. between said tension member and said framek to norma-ily .urge vthedriving. vmeans in one direction on. said supports, said frame having. an

' embossmentf atfthe end .of said duct, and said spring at one:.erick/havinga,l fasteningportion adapted :tooverlie saidsembossment, ahead stud .threaded in said .irame at saidembossment to clampingly secure .said fastening portion z onI the emhosslrient,V said stud having an exposed end. to facilitate manipulation of. the; same` in clamping ox:v releasing. theV fastening. .portion on said em` basement..

2;:'Ina parallel motion apparatus of the char.- acter'v mentioned, meansxcomprising an arm hav'- ingfpulleyfs-spaced apart thereon, flexible driving means. onsaid .pulleys and provided with av spring anchoragehoolr; a helicalspring connected at one-'endforr said hook, said spring. encircling said connected-.tothe otherxiend of the said spring and adjustable shiftablvon'. said arm to.:Y adjust the tension ofsaidfspring; and frictionV clampv means tcirsecllre@v said shift-,ably adjustable member Yin adjusted position ori-said arm;

Bt. In .aa parallelmotion apparatus of the char aeter mentioned, means. comprising' an arm having. pulleys. spacedfapart thereon, flexible driving means. on said pulleysl and provided with a spring anchorage hook, a: helicalv spring. connected at one end on said hook, said spring encircling said exibledriving meansan adjustable member connected to the other end of Athesaid spring land adjustable-.shiftably Yon said arm `to adjust the tension of said spring's,-and a headr studon said adjusted Vposition on said arm.

armf-operable-.to clamp theshiftable member -in 

